Lapping tool



Patented Feb. 1, 1944 LAPPING TOOL Foster F. Hillix, Lakewood, Ohio, assignor to The American Steel and Wire Company of New Jersey, a corporation of New Jersey No Drawing.

Original application April 10, 1939,

Serial No. 267,127. Divided and this application August 15, 1942, Serial No. 454,993

3 Claims.

This invention relates to lapping tools and the like, this application being a division of my pending application Serial No. 267,127, filed April 10, 1939.

My invention contemplates a lapping tool particularly adapted for use as a finishing" lap with suitable granular abrasive to completesthe' finishing operation upon hard objects such as metal-working rolls and the like.

I have discovered that lapping tools composed of a friable metal composition produce highly satisfactory results for the purposes stated, and that lead, tin, bismuth and mercury, when combined in substantially the following proportions is particularly suitable for such a "finishing" lap when molded into block form:

Parts by weight Lead 60-70 Tin 10-25 Bismu 20-30 Mercury 15 the foregoing proportions, the following composition may be employed to produce a finish on the work of high color:

Parts by weight 70 Lead Tin 25 Bismuth--- 20 Mercury 15 The abrasive to be used to greatest advantage with this lap is finely graded No. 5 lens powder.

The foregoing lap may be followed in finishing operations with a. lap having the following composition Parts by weight Lead 60 Bismuth 80 Mercury 15 Tin Such a lap develops a very high color on the work. By the use of this lap, microscopic analysis reveals that the surface of the work acquires a very high lustre therefrom.

The desirable characteristics attributable to the metals specified are those which will provide sufficient mechanical strength to enable the grain to cut, and yet, which will be soft enough to charge with abrasives, and sufficiently granular to wear away so as to obviate bunching or seizing of the cuttings and abrasive grains; and which will also provide a surface of the requisite porosity to receive the latter in order that they may be retired harmlessly from pressure contact with the surface of the work.

Various changes and modifications are contemplated within the scope of the following claims.

I claim:

1. A finishing lap consisting of a friable composition molded into block form containing approximately, by weight, to parts of lead, 10 to 25 parts of tin, 20 to 30 parts of bismuth, and 15 parts of mercury, characterized by having suflicient strength to apply a cutting pressure thereby to a fine polishing powder, and being soft enough to become charged with said powder.

2. A finishing lap consisting of a friable composition molded into block form containing approximately, by weight, 70 parts of lead, 20 parts of bismuth, 25 parts of tin, and 15 parts of mercury, characterized by having sufficient strength to apply a cutting pressure thereby to a fine polishing powder, and being soft enough to become charged with said powder.

3. A finishing lap consisting of a friable composition molded into block form containing approximately, by weight, 60 parts of lead, 30 parts of bismuth, 15 parts of mercury, and 10 parts of tin, characterized by having suflicient strength to apply a cutting pressure thereby to a fine polishing powder, and being soft enough to become charged with said powder.

ros'mn r'. max 

